sigh Firstly, it IS a game, and obviously they want this feature to launch well, and there is no sense in imposing an artificial limitation when intuitively the system should allow you to do what you think it should. "Colonize space and build empires." Secondly, people are going to try and brute force the system and create "Colony Inchworms" that will slowly crawl out to where they want to go, and THEN the actual intention of the system people are wanting to do can begin. I say, just go to that part and call it a day. Don't belabor the fun.
To your second point. Infrastructure my dude, no man is an island and no system is self sustaining. One of the endpoints that is being sold here, is that the players are building their own empires. Which is cool. You grow your empire from where you start. Allow the player to plant their flag where they want (barring some exemptions that Fdev can flag in the database as "NoGo" zones.) and allow the player and their group to grow from there. and actually colonize the galaxy. Whether it be "their private corner in the back water of space" or a huge squadron/Player Faction building a minibubble near Sag A. To that low life CMDR building casinos and "girls girls girls" signs flashing near their night clubs. The goal here is to unleash player freedom, not curtail it.
If you want a game design reason, it's to prevent "system squatting". So one or few players can't just "squat" on the well known, choice or key systems with the beacons hundreds or even thousands, or tens of thousands of lightyears apart.
I'm honestly envisioning the system much like fleet carriers where accounts only get ONE "global beacon" much like how you can only have one fleet carrier. And if you want that global beacon back, you got to roll up and dismantle everything, decommission everything (which itself sounds like a process you need to commit to.) Since this is colonization, as in a permanent structure change being put into the game, this SHOULD be something taking with serious consideration, whether a player wants to finance this in the first place, and then deeply consider where they want to plant this. So that alone already filters out 95% of the riffraff.
My worry is this feature will be gimped to try and address this hypothetical "system squatter" concern, that I don't think will actually be the issue they think it is. and more over, I think gimping it this way, will create a NEW problem the "Colony Inchworm" which WILL have an effect on the servers, since people will brute force it, creating a plethora of unnecessary system colonies JUST to get out to where they want.
I've been playing this game 10 years, and honestly I am just tired of Fdev delivering a broken or gimped feature, and they take 2+ years fixing it, if at all, of issues that should have been addressed in the design phase. and some of them simple problems. I just want this work out of the box. So let's avoid the waste of time, and more importantly server resources, as well as it becoming an eyesore, and the "unfun" of it all and
just.... let.... people.... colonize..... where.... they.... want.... on the outset.